OBD-II Code
P1340
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$180–$2,800
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$180 (CMP sensor + harness pigtail) to $2,800 (full phaser/chain job on a 5.4L 3V Triton).
P1340 in the Ford definition is a Camshaft Position Sensor B circuit fault on bank 1 — most commonly seen on the 4.6L/5.4L 3V Triton and other Ford Modular V8s that use separate CMP sensors per bank or per cam (intake/exhaust on VCT-equipped 3V heads).
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP1340 in the Ford definition is a Camshaft Position Sensor B circuit fault on bank 1 — most commonly seen on the 4.6L/5.4L 3V Triton and other Ford M…
P1340 in the Ford definition is a Camshaft Position Sensor B circuit fault on bank 1 — most commonly seen on the 4.6L/5.4L 3V Triton and other Ford Modular V8s that use separate CMP sensors per bank or per cam (intake/exhaust on VCT-equipped 3V heads). The PCM expects to see a clean digital pulse train from the CMP correlated with the CKP signal; P1340 sets when those pulses are missing, noisy, or out of phase with the crank.
Cheapest-first ladder
- Scope the CMP signal at the PCM connector — should be a clean 0-5 V square wave that correlates one-pulse-per-cam-revolution with the CKP pulses; missing pulses or noise spikes are the signature of a cracked sensor or a chewed reluctor.
- Pull the sensor and inspect the tip — metallic debris stuck to the magnetic tip is the smoking gun for cam-phaser tooth wear on a 3V Triton (the phaser is wearing internally and shedding metal onto the CMP).
- Ohm the CMP harness pin-to-pin from sensor to PCM — Ford specs sub-5-ohm continuity; corrosion at the CMP connector (which sits where it catches valve-cover oil weep) is a $40 fix vs. a $300 sensor. Critical caveat: don't replace the CMP sensor before reading keep-alive memory for cam phaser DTCs (P0012, P0014, P0022, P0024) — if those are present along with P1340, the real problem is the variable cam timing phasers themselves, not the sensor, and replacing only the sensor returns the customer 200 miles later for the same code plus a now-rattling top-end. Also check KAM for unauthorized tunes — VCT-disable tunes are common on 3V Tritons and can leave the PCM commanding cam-timing strategies the hardware doesn't follow, which sets P1340 as a secondary symptom.
Vehicle-specific patterns2004-2010 Ford F-150 / Expedition / Navigator with the 5.4L 3V Triton is the absolute canonical P1340 — the variable cam phasers wear internally, the…
- 2004-2010Ford F-150 / Expedition / Navigator with the 5.4L 3V Triton is the absolute canonical P1340 — the variable cam phasers wear internally, the timing-chain tensioners weaken, the phasers rattle on cold start, and the CMP sensor reads garbage data because the cam is no longer in sync with the crank; the proper fix is a full phaser + chain + tensioner + guide service ($1800-$2800 in labor alone).
- 2005-2010Ford Mustang GT 4.6L 3V sees the same pattern with lower frequency since Mustangs typically have lower miles than work trucks.
- 2007-2014Ford Edge / Lincoln MKX / Explorer with the 3.5L Duratec V6 throws P1340 from a similar cam-phaser wear pattern.
- 2011-2016Ford F-150 5.0L Coyote sees P1340 occasionally from VCT solenoid screen clogging (gold-screen oil-filtration screen at the solenoid clogs with sludge on extended oil-change intervals); a $80 solenoid + screen clean clears it.
Estimated repair$180 (CMP sensor + harness pigtail) to $2,800 (full phaser/chain job on a 5.4L 3V Triton).
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